In most automated 3D vision inspection systems, 3D measurements are combined with a 2D analysis, which in many cases implies the use of two separate acquisition stations. Consequently, it is difficult to take advantage of preliminary 2D results to improve the 3D analysis.
The well-known Fast Moiré Interferometry (FMI) method is based on a combination of structured light projection and phase-shift method for 3D information extraction at each point in an image. The FIG. 1 presents an example of FMI system. The FMI method uses the acquisition and analysis of several images with different grating projection. The 3D information extraction is based on an evaluation of intensity variation of each point with structured light modification. Basically, the FMI method analyses a point intensity variation with projected grating modification. The FMI method involves acquiring of a plurality of images and allows reconstructing an additional image corresponding to a configuration of lighting without any grid. Such a reconstructed image is useful for subsequent 2D analysis. However, this reconstructed image corresponds to a given configuration with lighting under an angle and does not give the possibility to identify some particularities of inspected components, since in such configuration, some elements thereof may be barely or even not visible, resulting in a less detailed and slower acquisition.
The U.S. Pat. No. 5,646,733 presents a non-invasive measuring method and system based on a Shadow Moiré configuration wherein the object under inspection is moved relative to an optical head, in such a way that multiple images with different phases are obtained.
Other approaches allow acquiring consecutive images with different illuminations by turning on each one of a number of illumination sources successively. However, since such a method requires light sources commutation, additional images acquisition results in an increase of inspection duration.
There is a need in the art for a 3D and 2D measurement system and method allowing a detailed thorough and fast examination of an object.